Pump motor having submersible stator and rotor and insulated winding set terminals

This is a continuation-in-part of U.S. application Ser. No. 08/961,856, filed on Oct. 31, 1997 now abandoned.

The present invention relates to a pump motor having a rotary pump for water or other liquids and an electric motor for driving the pump, which has fluid flow path structure permitting the rotor and stator to be submerged in fluid.

Water pump motors typically include a rotor assembly mounted in a rotor chamber and a stator assembly, having laminations and a winding set, operatively associated with the rotor assembly. The rotor assembly shares a bearing-supported shaft with an impeller of the pump. Water pump motors generally have some type of cooling to extend the operating capability thereof. In general, it is desirable to maintain the temperature of such devices below a predetermined limit in order to prevent deterioration of the device through thermal breakdown or distortion due to thermal expansion of elements of the device. In certain pump motors, the stator assembly and rotor assembly may be in fluid contact to cool the same, and the bearings may be in heat exchange relation with the fluid.

Water pump motors for use in todays automobiles are electronically controlled and generally have an electronic control unit electrically coupled to the winding set of the motor. The electronic control unit generates heat that may limit the operating temperature of the pump motor. Thus, there is a need to provide cooling not only of the bearings, rotor assembly and stator assembly of the device, but also of the electronic control unit thereof.

An object of the present invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a brushless electric motor including a stator assembly defining an interior chamber. The stator assembly includes a stator core and windings. The windings and at least a portion of the stator core are in open communication with the interior chamber. A rotor assembly is provided in the interior chamber. An electronic control unit is coupled to the stator assembly and has an upper surface in communication with the interior chamber. A fluid flow path structure is constructed and arranged to permit fluid to pass from an inlet in the stator assembly and enter the interior chamber so that the rotor assembly, the windings, and the portion of said stator core are submerged in the fluid for cooling the rotor assembly, the windings, and the portion of the stator core. Fluid also contacts the upper surface of the electronic control unit to cool the electronic control unit. Fluid isolating structure prevents fluid from contacting an end of the windings.

In accordance with another aspect of the invention, a method of isolating an end of a winding of a motor is provided. The motor has a stator assembly including a stator core and a winding which has a winding end. A rotor assembly is mounted for rotation with respect to the stator core. An electronic control unit is coupled to the stator assembly. The winding, the rotor assembly, a surface of the electronic control unit, and at least a portion of the stator core are constructed and arranged to be submerged in fluid. The method includes:

providing gasket material between the stator assembly and the electronic control unit; and

passing the winding end through the gasket material so as to prevent fluid from contacting the winding end when the winding, the rotor assembly, the surface of the electronic control unit, and the portion of the stator core are submerged in fluid.

Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawing, all of which form a part of this specification.

FIG. 1 is a sectional view of a water pump motor provided in accordance with the principles of the present invention,

FIG. 2 is an enlarged view of a winding set connection of the water pump motor of FIG. 1; and

FIG. 3 is a sectional view taken in the direction of the arrow A of FIG. 2 .

Referring to FIG. 1, a brushless d.c. water pump motor is shown generally indicated at 10 , which embodies the principles of the present invention.

The water pump motor 10 includes a pump housing 12 defining an impeller chamber 14 . An impeller 16 is disposed in the impeller chamber 14 . The pump housing and impeller may be of any conventional type having an exit 18 at an outer or high pressure portion 20 of the impeller chamber 14 , and an inlet 22 at a low pressure portion 24 of the impeller chamber 14 .

A motor assembly, generally indicated at 26 , is coupled to the pump housing 12 via bolting 30 . The motor assembly 26 includes a stator assembly, generally indicated at 32 , having the conventional laminations or stator core 34 and windings 36 . The stator assembly 32 defines a generally cylindrical interior chamber 38 and a rotor assembly 42 is disposed in the interior chamber 38 . As shown in the FIG. 1, the windings 36 and a portion 44 of the laminations 34 or stator core are in open fluid communication with the interior chamber 38 . The rotor assembly 42 has the conventional magnets 45 mounted on the outer peripheral portion thereof.

A shaft 46 is provided on which the rotor assembly 42 and impeller 16 are mounted. The shaft 46 is hollow and thus fluidly communicates the interior chamber 38 with the impeller chamber 14 via passage 47 therethrough. The shaft 46 is mounted for rotation via bearing 48 and bearing 49 that are operatively associated with the shaft 46 for supporting the hollow shaft 46 for rotational movement. Bearings 48 and 49 are housed in a bearing housing, generally indicated at 50 , which includes a boss portion 52 , and a generally disk-shaped portion 54 which is coupled to the stator assembly 32 .

An electronic control unit 60 containing the circuitry to operate the water pump motor 10 is coupled to the motor assembly 26 (in particular, to the stator assembly 32 ) and has an upper surface 62 in communication with the interior chamber 38 . Surface 62 may be part of a heat sink of the electronic control unit 60 .

In accordance with the principles of the invention, fluid flow path structure, generally indicated at 64 , is provided to permit fluid to pass from the high pressure portion 20 of the impeller chamber 14 to an inlet 66 of the motor assembly 26 and enter the interior chamber 38 so that the rotor assembly 42 , windings 36 and portion 44 of the stator core may be submerged in fluid and fluid may contact the upper surface 62 of the electronic control unit 60 to cool those assemblies. Further, the fluid may enter the hollow shaft 46 and be in heat transfer relation therewith to cool the bearings 48 and 49 .

In the embodiment of FIG. 1, the fluid flow path structure 64 includes a plurality of passages 70 through the stator assembly 32 and in particular through laminations 34 so as to be in fluid communication with interior chamber 38 . As shown, passages 70 also communicate with the upper surface 62 of the electronic control unit 60 . With reference to the arrows in FIG. 1, fluid may flow from the high pressure portion 20 of the impeller chamber 14 through the inlet 66 of the motor assembly 26 and through the passages 70 in the stator assembly 32 and into the interior chamber 38 . As a result, the rotor assembly 40 , windings 36 and portion 44 of the stator core 34 are submerged in the fluid and fluid contacts the upper surface 62 of the electronic control unit 60 to cool the same. The laminations 34 are also cooled by the fluid flowing through passages 70 in the stator assembly 32 . Fluid may pass through the passage 47 (fluid return structure) in the hollow shaft 46 and thus return fluid to the low pressure portion 24 of the impeller chamber 14 .

As shown in FIG. 1, a gasket 72 provides a seal between the pump housing 12 and the motor assembly 26 and a gasket 74 provides a seal between the stator assembly 32 and the electronic control unit 60 .

Thus, it can be seen that the rotor assembly, laminations, windings, bearing structure and the electronic control unit are cooled effectively by the circulating fluid.

FIG. 2 is an enlarged view of a winding set connection for the pump motor of FIG. 1 .

In order to isolate the winding terminals from cooling fluid in chamber 38 of the stator assembly 32 , the end portion 80 of the windings 36 is passed between a fluid isolating structure in the form of an elastomer gasket material 74 ′ which seals the stator assembly 32 with the electronic control unit 60 . Thus, cooling fluid is prevented from passing from chamber 38 to winding end 81 . The gasket material 74 ′ is preferably silicone material that is applied directly to a gasket channel 84 defined in the stator assembly 32 . The gasket material 74 ′ may be applied either manually or by a robotic dispensing system into the gasket channel 84 . In the preferred embodiment, the gasket material 74 ′ is applied without the electronic control unit 60 being attached to the stator assembly 32 . This is done by providing the gasket material in the gasket channel 84 and passing the winding end 81 therethrough in a molding process so as to surround the wire. Surface tension helps maintain the position of portion 74 ″ of the gasket material 74 ′. Thus, portion 74 ″ of the gasket material 74 ′ is free-formed. The gasket material 74 ′ is then cured preferably by UV light to form a compressible gasket. Other elastomers may be used as the gasket material 74 ′ which are capable of isolating the fluid from winding end 81 .

In addition, an electrical connection, generally indicated at 88 , is provided which joins winding end 81 to a printed circuit board socket 90 . This connection 88 is achieved via a tab 92 engaged at one end 94 with winding end 81 and, at the other end 96 thereof, to the socket 90 . As best shown in FIG. 3, end 94 of tab 92 is embedded in housing 82 and is a generally U-shaped or V-shaped having serrations 98 which engage the winding end 81 when the winding end 81 is passed therethrough. When the electronic control unit 60 is coupled to the stator assembly, a heat sink portion 100 of the electronic control unit 60 engages portion 74 ″ of the gasket material 74 ′. In addition, the end 96 of the tab 92 is removably engaged with the socket 90 . This arrangement isolates the winding terminals from cooling fluid in chamber 38 of the stator assembly 32 yet advantageously permits the electronic control unit 60 , upon failure thereof, to be removed from the stator assembly 32 without upsetting or destroying the gasket material 74 ′ and thus the seal surrounding the winding end 81 . This permits another electronic control unit 60 to be coupled to stator assembly 32 .

The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.